The ever-increasing world population and the dwindling supply of arable land available for agriculture fuel research towards improving the efficiency of agriculture. Conventional means for crop and horticultural improvements utilise selective breeding techniques to identify plants having desirable characteristics. However, such selective breeding techniques have several drawbacks, namely that these techniques are typically labour intensive and result in plants that often contain heterogeneous genetic components that may not always result in the desirable trait being passed on from parent plants. Advances in molecular biology have allowed mankind to modify the germplasm of animals and plants. Genetic engineering of plants entails the isolation and manipulation of genetic material (typically in the form of DNA or RNA) and the subsequent introduction of that genetic material into a plant. Such technology has the capacity to deliver crops or plants having various improved economic, agronomic or horticultural traits A trait of particular economic interest is yield. Yield is normally defined as the measurable produce of economic value from a crop. This may be defined in terms of quantity and/or quality. Crop yield may not only be increased by combating one or more stresses to which a crop or plant is typically subjected, but may also be increased by modifying the inherent growth characteristics of a plant. Yield is directly dependent on several growth characteristics, for example, growth rate, biomass production, plant architecture, number and size of organs, (for example, the number of branches, tillers, shoots, flowers), seed production and more. Root development and nutrient uptake may also be important factors in determining yield.
The ability to modify one or more plant growth characteristics, would have many applications in areas such as crop enhancement, plant breeding, production of ornamental plants, aboriculture, horticulture, forestry, production of algae or plants (for example for use as bioreactors, for the production of substances such as pharmaceuticals, antibodies, or vaccines, or for the bioconversion of organic waste or for use as fuel in the case of high-yielding algae and plants).